@hnahli you'll want to make a database dump, depending on your db it's different just search [your db] dump backup.
You'll also want to make a backup of your uploaded files if any.
Here's an okay resource: https://docs.nodebb.org/fr/latest/upgrading/index.html?highlight=backup#back-up-your-data
It's possible, but not easy. There are a few options:
create a theme for NodeBB, render NodeBB in an iframe and embed that in your page
render NodeBB templates in an angular component and embed that in your page
interface directly with the NodeBB rest API, creating a frontend in angular
@gorgiselkov I believe that one might not be working because it's a skeleton plugin, and not an actual SSO auth (as stated on github page), unless you've configured it yourself but, it doesn't seem like it.